US20150131408A1 - Laser-induced ultrasound generator and method of manufacturing the same - Google Patents
Laser-induced ultrasound generator and method of manufacturing the same Download PDFInfo
- Publication number
- US20150131408A1 US20150131408A1 US14/296,567 US201414296567A US2015131408A1 US 20150131408 A1 US20150131408 A1 US 20150131408A1 US 201414296567 A US201414296567 A US 201414296567A US 2015131408 A1 US2015131408 A1 US 2015131408A1
- Authority
- US
- United States
- Prior art keywords
- substrate
- laser
- layer
- ultrasound generator
- thermoelastic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K15/00—Acoustics not otherwise provided for
- G10K15/04—Sound-producing devices
- G10K15/046—Sound-producing devices using optical excitation, e.g. laser bundle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/14—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object using acoustic emission techniques
Definitions
- the exemplary embodiments relate to laser-induced ultrasound generators and methods of manufacturing the same.
- the irradiated material When a laser is irradiated onto a material such as a liquid or a solid, the irradiated material absorbs light energy to generate instant thermal energy, and the thermal energy generates an acoustic wave due to thermoelasticity of the material.
- ultrasound waves generated by different materials differ in amplitude in response to the same light energy.
- the generated ultrasound waves are used in an analyzer of materials, a non-destructive tester, and a photoacoustic tomography, or the like.
- a laser-induced ultrasound generator (hereinafter referred to as an ultrasound generator) is an apparatus for generating an ultrasound wave by using a laser.
- an ultrasound wave By using the ultrasound wave, it may be diagnosed as to whether, for example, tumors are formed in the body of a patient, that is, in an object.
- the ultrasound wave is generated based on the principle that energy of absorbed light is converted into pressure.
- a conventional laser-induced ultrasound generator uses a thermoelastic material layer having a low light absorption ratio, and thus, a low ultrasound generation efficiency.
- laser-induced ultrasound generators with an increased ultrasound generation efficiency.
- a laser-induced ultrasound generator including: a substrate including a plurality of nanostructures provided on a first surface of the substrate; and a thermoelastic layer provided on the first surface of the substrate, the thermoelastic layer being configured to generate an ultrasound by absorbing a laser beam incident onto a second surface of the substrate, the second surface facing the first surface.
- the plurality of nanostructures may include a plurality of cylinder-shaped nanopillars.
- Each of the plurality of nanopillars may have a diameter of about 10 nm to about 1000 nm.
- a gap between adjacent nanopillars may be about 10 nm to about 1000 nm.
- the thermoelastic layer may include a metal or a polymer material.
- the substrate may include a laser beam-transmitting material.
- the laser-induced ultrasound generator may further include a matching layer provided on the thermoelastic layer, wherein a surface of the matching layer faces the first surface of the substrate.
- the matching layer may include a polymer.
- the laser-induced ultrasound generator may further include a laser oscillator configured to irradiate the laser beam onto the second surface of the substrate.
- a method of manufacturing a laser-induced ultrasound generator including: forming a thin metal film on a substrate; converting the thin metal film into a plurality of metal dots by annealing the substrate; forming a plurality of nanostructures on the substrate by dry-etching the substrate, the dry-etching comprising using the plurality of metal dots as a mask; removing the plurality of metal dots; and forming a thermoelastic layer on the substrate to cover the plurality of nanostructures.
- the forming of the thin metal film may include forming a thin metal film having a thickness of about 10 nm to about 1000 nm.
- the converting of the thin metal film into the plurality of metal dots may include forming metal dots, each having a diameter of about 10 nm to about 1000 nm, as the plurality of metal dots.
- the forming of the plurality of nanostructures may include forming a plurality of nanopillars, each having a diameter corresponding to a size of one of the plurality of metal dots, as the plurality of nanostructures.
- the method may further include forming a matching layer on the thermoelastic layer, a surface of the matching layer facing a surface of the substrate.
- FIG. 1 is a schematic structural view of a ultrasound generator according to exemplary embodiments
- FIG. 2 is a scanning electron microscope (SEM) photographic image of nanopillars formed on a glass substrate
- FIG. 3 is a simulation graph showing light absorption ratios of an ultrasound generator having nanostructures according to exemplary embodiments and a conventional ultrasound generator without nanostructures;
- FIGS. 4A through 4E are cross-sectional views illustrating a method of manufacturing an ultrasound generator according to exemplary embodiments.
- FIG. 1 is a schematic structural view of an ultrasound generator 100 according to exemplary embodiments.
- the ultrasound generator 100 may include a substrate 110 through which a laser beam L is transmitted, and a thermoelastic layer 130 formed on the substrate 110 .
- a matching layer 150 may be further formed on the thermoelastic layer 130 .
- a laser oscillator 170 irradiates the laser beam L onto the substrate 110 .
- the substrate 110 may be formed of a material having a relatively high light transmittivity so that a laser beam L may be incident onto the thermoelastic layer 130 without any loss.
- the substrate 110 may be formed of quartz, fused silicon, glass or the like.
- the laser beam L may be incident onto a first surface 110 a of the substrate 110 , and a plurality of nanostructures may be formed on a surface of the substrate 110 opposite to the first surface 110 a.
- the nanostructures may be cylinder-shaped nanopillars 114 .
- the nanopillars 114 may be formed by etching the substrate 110 and thus, the nanopillars may be formed to be expanded from the substrate 110 .
- nanopillars 114 are illustrated as the nanostructures according to the current exemplary embodiment, the exemplary embodiments are not limited thereto.
- nano-cone structures may be formed as the nanostructures instead of the nanopillars 114 .
- the nanopillars 114 may have a diameter of about 10 nm to about 1000 nm, and a gap between adjacent nanopillars 114 may be about 10 nm to about 1000 nm.
- FIG. 2 is a scanning electron microscope SEM photographic image of the nanopillars 114 formed on the substrate 110 which is formed of glass.
- each of the nanopillars 114 may have an average diameter of about 100 nm, and a gap between adjacent nanopillars 114 may be about 100 nm. As illustrated in FIG. 2 , the nanopillars 114 may have different diameters from one another.
- the thermoelastic layer 130 expands upon absorbing an irradiated laser beam L, and an ultrasound U is generated according to the expansion of the thermoelastic layer 130 .
- the thermoelastic layer 130 may be formed of a material having a relatively high thermal expansion coefficient.
- the thermoelastic layer 130 may be a thin film so as to easily thermally expand or contract.
- the thickness of the thermoelastic layer 130 may be several ⁇ m or less.
- the thermoelastic layer 130 may be formed of a metal or a polymer material.
- the thermoelastic layer 130 may be formed of a metal such as Cr, Ti, Au, or Al or of a polymer material such as black polydimethylsiloxane (PDMS) mixed with carbon or carbon tapes.
- PDMS black polydimethylsiloxane
- the thermoelastic layer 130 may fill spaces between the nanopillars 114 .
- the thermoelastic layer 130 may completely fill spaces between the nanopillars 114 as illustrated in FIG. 1 .
- exemplary embodiments are not limited thereto.
- the thermoelastic layer 130 having a small thickness may be formed to partially fill spaces between the nanopillars 114 .
- thermoelastic layer 130 may be formed as a double layer.
- the thermoelastic layer 130 may include an adhesive layer formed of Ti or Cr and a metal layer including a material such as Au or Al on the adhesive layer.
- the matching layer 150 may modify acoustic impedance of an ultrasound U generated in the thermoelastic layer 130 stepwise so that the acoustic impedance of the ultrasound U is similar to that of an object.
- the thermoelastic layer 130 may be a single layer or may be formed of a plurality of layers.
- the matching layer 150 may be formed of a polymer material.
- the matching layer 150 may be formed of parylene, polydimethylsiloxane (PMDS) or polyimide.
- the matching layer 150 on the thermoelastic layer 130 may be omitted.
- the thermoelastic layer 130 is formed of a polymer material, the matching layer 150 may be omitted.
- the laser oscillator 170 irradiates the laser beam L onto the substrate 110 , from which an ultrasound U is generated.
- the laser oscillator 170 may be a pulse laser, and a pulse width of the laser may be in the range of nanoseconds or picoseconds.
- an ultrasound U is generated in the thermoelastic layer 130 due to thermoelasticity.
- the ultrasound U is irradiated onto an object, a portion of the ultrasound U is absorbed by the object, and the remainder of the ultrasound U is reflected.
- a signal reflected by the object that is, an echo signal of the ultrasound U
- a shape of the object and characteristics of tissues of the object may be measured.
- the ultrasound generator 110 may convert light into the ultrasound U based on the following principle.
- the thermoelastic layer 130 When light having an energy density of I(x, y, z, t) is irradiated onto the thermoelastic layer 130 , the thermoelastic layer 130 generates heat H as expressed as in Equation 1 below.
- R denotes a reflection coefficient of a thermoelastic layer with respect to the light
- ⁇ denotes an absorption coefficient of the thermoelastic layer with respect to the laser beam
- z denotes a vertical distance between the thermoelastic layer and a surface onto which the laser beam is incident.
- thermoelastic layer a variation in temperature ( ⁇ T) as expressed in Equation 2 below is generated.
- k denotes a thermal conductivity of the thermoelastic layer
- C denotes a heat propagation speed in the thermoelastic layer
- ⁇ denotes a density of the thermoelastic layer
- Cp denotes a specific heat of the thermoelastic layer.
- Equation 3 Due to the variation in temperature ( ⁇ T), a variation in volume ( ⁇ V) as in Equation 3 below is generated in the thermoelastic layer.
- ⁇ denotes a thermal coefficient of volume of the thermoelastic layer.
- Equation 4 An ultrasound having a pressure P as expressed in Equation 4 below is generated according to the variation in volume ( ⁇ V) of the thermoelastic layer.
- v s denotes a speed at which the ultrasound travels.
- thermoelastic layer in the ultrasound generator, an ultrasound generation efficiency may be improved only by increasing the light absorption ratio of the thermoelastic layer.
- the nanopillars 114 are formed between the substrate 110 , which is an insulation material, and the thermoelastic layer 130 , and thus, light irradiated onto the nanopillars 114 generates surface plasmon polaritons between the substrate 110 and the thermoelastic layer 130 . If the nanopillars 114 , which are nanostructures in a three-dimensional shape, are formed between the substrate 110 and the thermoelastic layer 130 , the surface plasmon polaritons become trapped in the nanostructures, and a light absorption ratio in the thermoelastic layer 130 is increased. Thus, an ultrasound generation efficiency may be improved.
- FIG. 3 is a simulation graph showing light absorption ratios of an ultrasound generator having nanostructures according to exemplary embodiments and a conventional ultrasound generator without nanostructures.
- the ultrasound generator according to the current exemplary embodiment includes a thermoelastic layer formed by depositing a 50 nm thick Au layer, and 2 ⁇ m thick parylene layer as a matching layer, and glass is used as a substrate. Nanopillars have a width, height, and interval which are each 100 nm.
- the conventional ultrasound generator has the same structure as the current exemplary embodiment except that the substrate and the thermoelastic layer are flat.
- a first curve C 1 denotes a light absorption ratio of the ultrasound generator according to the current exemplary embodiment
- a second curve C 2 denotes a light absorption ratio of the conventional ultrasound generator.
- a light absorption ratio of the ultrasound generator having nanostructures is larger than that of the conventional ultrasound generator.
- a laser beam wavelength is 550 nm
- a light absorption ratio of the conventional ultrasound generator is about 0.3
- that of the ultrasound generator according to the current exemplary embodiment is about 0.7.
- the light absorption ratio of the ultrasound generator according to the current exemplary embodiment is greater than that of the conventional ultrasound generator.
- thermoelastic layer of the ultrasound generator of the current exemplary embodiment has an increased light absorption ratio due to a function of the nanopillars formed between the substrate and the thermoelastic layer. Furthermore, when the same laser energy is used in the ultrasound generator of the current exemplary embodiment and the conventional ultrasound generator, the ultrasound generator of the current exemplary embodiment generates an ultrasound having a pressure greater than that of an ultrasound generated by the conventional ultrasound generator.
- FIGS. 4A through 4E are cross-sectional views illustrating a method of manufacturing an ultrasound generator according to exemplary embodiments.
- a metal layer 220 having a first thickness H 1 is deposited on a substrate 210 .
- the metal layer 220 may be formed of a typical metal such as Ag, Au or Pb. If a metal for the metal layer 220 has contracting properties upon being heated, then the metal for the metal layer 220 is not limited to a predetermined material as above.
- the first thickness H 1 may be about 10 nm to about 1000 nm.
- the substrate 210 may be formed of, for example, quartz, fused silica or glass.
- the substrate 210 is annealed.
- An annealing temperature may vary according to the material of the metal layer 220 and the first thickness H 1 .
- a plurality of metal dots 222 is formed on the substrate 210 .
- Each of the metal dots 222 may have a size of about 10 nm to about 1000 nm, and a distance between the metal dots 222 may also be about 10 nm to about 1000 nm.
- the metal dots 222 are used as a mask to dry-etch the substrate 210 .
- a plurality of cylinder-shaped nanopillars 214 is formed on the substrate 210 .
- An aspect ratio of the nanopillars 214 may be about 1.
- the nanopillars 214 may have a diameter of about 10 nm to about 1000 nm, and a gap between adjacent nanopillars 214 may be about 10 nm to about 1000 nm.
- the substrate 210 is dipped into a solution which is capable of removing the metal dots 222 , thereby removing the metal dots 222 from the substrate 210 .
- FIG. 4C illustrates the substrate 210 before the metal dots 222 are removed.
- thermoelastic layer 230 covering the nanopillars 214 is formed on the substrate 210 .
- the thermoelastic layer 230 may be formed of a metal or a polymer material.
- the thermoelastic layer 230 may be formed of a metal such as Cr, Ti, Au, or Al or of a polymer material such as black polydimethylsiloxane (PDMS) mixed with carbon or carbon tapes. If the thermoelastic layer 230 is formed of a metal, the thermoelastic layer 230 may be formed as a double layer.
- the thermoelastic layer 230 may include an adhesive layer formed of Ti or Cr and a metal layer including Au or Al on the adhesive layer.
- a matching layer 250 may be formed on the thermoelastic layer 230 .
- the matching layer 250 may be formed of a polymer material.
- the matching layer 250 may be formed of parylene, PMDS, or polyimide.
- the matching layer 250 may have a thickness of about several gm.
- the matching layer 250 may be formed of a plurality of layers. Also, the matching layer 250 may be formed of a plurality of layers that are formed of different materials.
- thermoelastic layer 230 is formed of a polymer material
- the matching layer 250 may be omitted.
Abstract
Description
- This application claims priority to Korean Patent Application No. 10-2013-0136302, filed on Nov. 11, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
- 1. Field
- The exemplary embodiments relate to laser-induced ultrasound generators and methods of manufacturing the same.
- 2. Description of the Related Art
- When a laser is irradiated onto a material such as a liquid or a solid, the irradiated material absorbs light energy to generate instant thermal energy, and the thermal energy generates an acoustic wave due to thermoelasticity of the material.
- As an absorption ratio and a thermoelastic coefficient of materials vary according to a light wavelength of the materials, ultrasound waves generated by different materials differ in amplitude in response to the same light energy. The generated ultrasound waves are used in an analyzer of materials, a non-destructive tester, and a photoacoustic tomography, or the like.
- A laser-induced ultrasound generator (hereinafter referred to as an ultrasound generator) is an apparatus for generating an ultrasound wave by using a laser. By using the ultrasound wave, it may be diagnosed as to whether, for example, tumors are formed in the body of a patient, that is, in an object. The ultrasound wave is generated based on the principle that energy of absorbed light is converted into pressure.
- A conventional laser-induced ultrasound generator uses a thermoelastic material layer having a low light absorption ratio, and thus, a low ultrasound generation efficiency.
- Provided are laser-induced ultrasound generators with an increased ultrasound generation efficiency.
- Provided are methods of manufacturing the laser-induced ultrasound generators.
- Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented exemplary embodiments.
- According to an aspect of an exemplary embodiment, there is provided a laser-induced ultrasound generator including: a substrate including a plurality of nanostructures provided on a first surface of the substrate; and a thermoelastic layer provided on the first surface of the substrate, the thermoelastic layer being configured to generate an ultrasound by absorbing a laser beam incident onto a second surface of the substrate, the second surface facing the first surface.
- The plurality of nanostructures may include a plurality of cylinder-shaped nanopillars.
- Each of the plurality of nanopillars may have a diameter of about 10 nm to about 1000 nm.
- A gap between adjacent nanopillars may be about 10 nm to about 1000 nm.
- The thermoelastic layer may include a metal or a polymer material.
- The substrate may include a laser beam-transmitting material.
- The laser-induced ultrasound generator may further include a matching layer provided on the thermoelastic layer, wherein a surface of the matching layer faces the first surface of the substrate.
- The matching layer may include a polymer.
- The laser-induced ultrasound generator may further include a laser oscillator configured to irradiate the laser beam onto the second surface of the substrate.
- According to another aspect of an exemplary embodiment, there is provided a method of manufacturing a laser-induced ultrasound generator, the method including: forming a thin metal film on a substrate; converting the thin metal film into a plurality of metal dots by annealing the substrate; forming a plurality of nanostructures on the substrate by dry-etching the substrate, the dry-etching comprising using the plurality of metal dots as a mask; removing the plurality of metal dots; and forming a thermoelastic layer on the substrate to cover the plurality of nanostructures.
- The forming of the thin metal film may include forming a thin metal film having a thickness of about 10 nm to about 1000 nm.
- The converting of the thin metal film into the plurality of metal dots may include forming metal dots, each having a diameter of about 10 nm to about 1000 nm, as the plurality of metal dots.
- The forming of the plurality of nanostructures may include forming a plurality of nanopillars, each having a diameter corresponding to a size of one of the plurality of metal dots, as the plurality of nanostructures.
- The method may further include forming a matching layer on the thermoelastic layer, a surface of the matching layer facing a surface of the substrate.
- These and/or other aspects will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings in which:
-
FIG. 1 is a schematic structural view of a ultrasound generator according to exemplary embodiments; -
FIG. 2 is a scanning electron microscope (SEM) photographic image of nanopillars formed on a glass substrate; -
FIG. 3 is a simulation graph showing light absorption ratios of an ultrasound generator having nanostructures according to exemplary embodiments and a conventional ultrasound generator without nanostructures; and -
FIGS. 4A through 4E are cross-sectional views illustrating a method of manufacturing an ultrasound generator according to exemplary embodiments. - Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings, wherein thicknesses of layers or regions illustrated in the drawings are exaggerated for clarity of description. In this regard, the present exemplary embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element, or intervening elements may also be present. Like reference numerals refer to the like elements throughout and a detailed description thereof will be omitted.
-
FIG. 1 is a schematic structural view of anultrasound generator 100 according to exemplary embodiments. - Referring to
FIG. 1 , theultrasound generator 100 may include asubstrate 110 through which a laser beam L is transmitted, and athermoelastic layer 130 formed on thesubstrate 110. A matchinglayer 150 may be further formed on thethermoelastic layer 130. Alaser oscillator 170 irradiates the laser beam L onto thesubstrate 110. - The
substrate 110 may be formed of a material having a relatively high light transmittivity so that a laser beam L may be incident onto thethermoelastic layer 130 without any loss. Thesubstrate 110 may be formed of quartz, fused silicon, glass or the like. The laser beam L may be incident onto afirst surface 110 a of thesubstrate 110, and a plurality of nanostructures may be formed on a surface of thesubstrate 110 opposite to thefirst surface 110 a. The nanostructures may be cylinder-shaped nanopillars 114. Thenanopillars 114 may be formed by etching thesubstrate 110 and thus, the nanopillars may be formed to be expanded from thesubstrate 110. - Although the
nanopillars 114 are illustrated as the nanostructures according to the current exemplary embodiment, the exemplary embodiments are not limited thereto. For example, nano-cone structures may be formed as the nanostructures instead of thenanopillars 114. - The
nanopillars 114 may have a diameter of about 10 nm to about 1000 nm, and a gap betweenadjacent nanopillars 114 may be about 10 nm to about 1000 nm. -
FIG. 2 is a scanning electron microscope SEM photographic image of thenanopillars 114 formed on thesubstrate 110 which is formed of glass. Referring toFIG. 2 , each of thenanopillars 114 may have an average diameter of about 100 nm, and a gap betweenadjacent nanopillars 114 may be about 100 nm. As illustrated inFIG. 2 , thenanopillars 114 may have different diameters from one another. - The
thermoelastic layer 130 expands upon absorbing an irradiated laser beam L, and an ultrasound U is generated according to the expansion of thethermoelastic layer 130. Thethermoelastic layer 130 may be formed of a material having a relatively high thermal expansion coefficient. Thethermoelastic layer 130 may be a thin film so as to easily thermally expand or contract. For example, the thickness of thethermoelastic layer 130 may be several μm or less. Thethermoelastic layer 130 may be formed of a metal or a polymer material. For example, thethermoelastic layer 130 may be formed of a metal such as Cr, Ti, Au, or Al or of a polymer material such as black polydimethylsiloxane (PDMS) mixed with carbon or carbon tapes. - The
thermoelastic layer 130 may fill spaces between thenanopillars 114. Thethermoelastic layer 130 may completely fill spaces between thenanopillars 114 as illustrated inFIG. 1 . However, exemplary embodiments are not limited thereto. For example, thethermoelastic layer 130 having a small thickness may be formed to partially fill spaces between thenanopillars 114. - If the
thermoelastic layer 130 is formed of the metal, thethermoelastic layer 130 may be formed as a double layer. For example, thethermoelastic layer 130 may include an adhesive layer formed of Ti or Cr and a metal layer including a material such as Au or Al on the adhesive layer. - The
matching layer 150 may modify acoustic impedance of an ultrasound U generated in thethermoelastic layer 130 stepwise so that the acoustic impedance of the ultrasound U is similar to that of an object. Thethermoelastic layer 130 may be a single layer or may be formed of a plurality of layers. Thematching layer 150 may be formed of a polymer material. For example, thematching layer 150 may be formed of parylene, polydimethylsiloxane (PMDS) or polyimide. - The
matching layer 150 on thethermoelastic layer 130 may be omitted. In particular, if thethermoelastic layer 130 is formed of a polymer material, thematching layer 150 may be omitted. - The
laser oscillator 170 irradiates the laser beam L onto thesubstrate 110, from which an ultrasound U is generated. For example, thelaser oscillator 170 may be a pulse laser, and a pulse width of the laser may be in the range of nanoseconds or picoseconds. - After the laser beam L is transmitted through the
substrate 110 and then is irradiated onto thethermoelastic layer 130, an ultrasound U is generated in thethermoelastic layer 130 due to thermoelasticity. The ultrasound U is irradiated onto an object, a portion of the ultrasound U is absorbed by the object, and the remainder of the ultrasound U is reflected. By receiving a signal reflected by the object, that is, an echo signal of the ultrasound U, a shape of the object and characteristics of tissues of the object may be measured. - The
ultrasound generator 110 may convert light into the ultrasound U based on the following principle. When light having an energy density of I(x, y, z, t) is irradiated onto thethermoelastic layer 130, thethermoelastic layer 130 generates heat H as expressed as inEquation 1 below. -
H=(1−R)·I·μe μz ([Equation 1] - Here, R denotes a reflection coefficient of a thermoelastic layer with respect to the light, and μ denotes an absorption coefficient of the thermoelastic layer with respect to the laser beam, and z denotes a vertical distance between the thermoelastic layer and a surface onto which the laser beam is incident.
- In the thermoelastic layer, a variation in temperature (ΔT) as expressed in Equation 2 below is generated.
-
- Here, k denotes a thermal conductivity of the thermoelastic layer, C denotes a heat propagation speed in the thermoelastic layer, ρ denotes a density of the thermoelastic layer, and Cp denotes a specific heat of the thermoelastic layer.
- Due to the variation in temperature (ΔT), a variation in volume (ΔV) as in Equation 3 below is generated in the thermoelastic layer.
-
- Here, β denotes a thermal coefficient of volume of the thermoelastic layer.
- An ultrasound having a pressure P as expressed in Equation 4 below is generated according to the variation in volume (ΔV) of the thermoelastic layer.
-
- Here, vs denotes a speed at which the ultrasound travels.
- If the same material is used for the thermoelastic layer in the ultrasound generator, an ultrasound generation efficiency may be improved only by increasing the light absorption ratio of the thermoelastic layer.
- According to exemplary embodiments, the
nanopillars 114 are formed between thesubstrate 110, which is an insulation material, and thethermoelastic layer 130, and thus, light irradiated onto thenanopillars 114 generates surface plasmon polaritons between thesubstrate 110 and thethermoelastic layer 130. If thenanopillars 114, which are nanostructures in a three-dimensional shape, are formed between thesubstrate 110 and thethermoelastic layer 130, the surface plasmon polaritons become trapped in the nanostructures, and a light absorption ratio in thethermoelastic layer 130 is increased. Thus, an ultrasound generation efficiency may be improved. -
FIG. 3 is a simulation graph showing light absorption ratios of an ultrasound generator having nanostructures according to exemplary embodiments and a conventional ultrasound generator without nanostructures. The ultrasound generator according to the current exemplary embodiment includes a thermoelastic layer formed by depositing a 50 nm thick Au layer, and 2 μm thick parylene layer as a matching layer, and glass is used as a substrate. Nanopillars have a width, height, and interval which are each 100 nm. The conventional ultrasound generator has the same structure as the current exemplary embodiment except that the substrate and the thermoelastic layer are flat. - Referring to
FIG. 3 , a first curve C1 denotes a light absorption ratio of the ultrasound generator according to the current exemplary embodiment, and a second curve C2 denotes a light absorption ratio of the conventional ultrasound generator. A light absorption ratio of the ultrasound generator having nanostructures is larger than that of the conventional ultrasound generator. When a laser beam wavelength is 550 nm, a light absorption ratio of the conventional ultrasound generator is about 0.3, while that of the ultrasound generator according to the current exemplary embodiment is about 0.7. Thus, the light absorption ratio of the ultrasound generator according to the current exemplary embodiment is greater than that of the conventional ultrasound generator. - Therefore, the thermoelastic layer of the ultrasound generator of the current exemplary embodiment has an increased light absorption ratio due to a function of the nanopillars formed between the substrate and the thermoelastic layer. Furthermore, when the same laser energy is used in the ultrasound generator of the current exemplary embodiment and the conventional ultrasound generator, the ultrasound generator of the current exemplary embodiment generates an ultrasound having a pressure greater than that of an ultrasound generated by the conventional ultrasound generator.
-
FIGS. 4A through 4E are cross-sectional views illustrating a method of manufacturing an ultrasound generator according to exemplary embodiments. - Referring to
FIG. 4A , ametal layer 220 having a first thickness H1 is deposited on asubstrate 210. Themetal layer 220 may be formed of a typical metal such as Ag, Au or Pb. If a metal for themetal layer 220 has contracting properties upon being heated, then the metal for themetal layer 220 is not limited to a predetermined material as above. The first thickness H1 may be about 10 nm to about 1000 nm. Thesubstrate 210 may be formed of, for example, quartz, fused silica or glass. - Referring to
FIG. 4B , thesubstrate 210 is annealed. An annealing temperature may vary according to the material of themetal layer 220 and the first thickness H1. After the annealing, a plurality ofmetal dots 222 is formed on thesubstrate 210. Each of themetal dots 222 may have a size of about 10 nm to about 1000 nm, and a distance between themetal dots 222 may also be about 10 nm to about 1000 nm. - Referring to
FIG. 4C , themetal dots 222 are used as a mask to dry-etch thesubstrate 210. After etching, a plurality of cylinder-shapednanopillars 214 is formed on thesubstrate 210. An aspect ratio of thenanopillars 214 may be about 1. Thenanopillars 214 may have a diameter of about 10 nm to about 1000 nm, and a gap betweenadjacent nanopillars 214 may be about 10 nm to about 1000 nm. - The
substrate 210 is dipped into a solution which is capable of removing themetal dots 222, thereby removing themetal dots 222 from thesubstrate 210.FIG. 4C illustrates thesubstrate 210 before themetal dots 222 are removed. - Referring to
FIG. 4D , athermoelastic layer 230 covering thenanopillars 214 is formed on thesubstrate 210. Thethermoelastic layer 230 may be formed of a metal or a polymer material. For example, thethermoelastic layer 230 may be formed of a metal such as Cr, Ti, Au, or Al or of a polymer material such as black polydimethylsiloxane (PDMS) mixed with carbon or carbon tapes. If thethermoelastic layer 230 is formed of a metal, thethermoelastic layer 230 may be formed as a double layer. For example, thethermoelastic layer 230 may include an adhesive layer formed of Ti or Cr and a metal layer including Au or Al on the adhesive layer. - Referring to
FIG. 4E , amatching layer 250 may be formed on thethermoelastic layer 230. Thematching layer 250 may be formed of a polymer material. For example, thematching layer 250 may be formed of parylene, PMDS, or polyimide. Thematching layer 250 may have a thickness of about several gm. Thematching layer 250 may be formed of a plurality of layers. Also, thematching layer 250 may be formed of a plurality of layers that are formed of different materials. - When the
thermoelastic layer 230 is formed of a polymer material, thematching layer 250 may be omitted. - According to the method of manufacturing a laser-induced ultrasound generator, as metal dots formed by annealing are used in forming nanopillars, an additional mask process involving a nano-sized mask is not required.
- It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each exemplary embodiment should typically be considered as available for other similar features or aspects in other exemplary embodiments.
- While one or more exemplary embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the following claims.
Claims (17)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR10-2013-0136302 | 2013-11-11 | ||
KR1020130136302A KR20150054179A (en) | 2013-11-11 | 2013-11-11 | Laser-induced ultrasound generator and method of fabricating the same |
Publications (2)
Publication Number | Publication Date |
---|---|
US20150131408A1 true US20150131408A1 (en) | 2015-05-14 |
US9865246B2 US9865246B2 (en) | 2018-01-09 |
Family
ID=53043705
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/296,567 Active 2035-08-08 US9865246B2 (en) | 2013-11-11 | 2014-06-05 | Laser-induced ultrasound generator and method of manufacturing the same |
Country Status (2)
Country | Link |
---|---|
US (1) | US9865246B2 (en) |
KR (1) | KR20150054179A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3220387A1 (en) | 2016-03-15 | 2017-09-20 | Haute Ecole Arc Ingénierie | Photoacoustic device and method for manufacturing a photoacoustic device |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR102018215B1 (en) * | 2017-11-28 | 2019-09-04 | 한국세라믹기술원 | Microscale and nanoscale pattern and that method for controlling the shape |
KR102097218B1 (en) * | 2018-11-16 | 2020-04-03 | 한국세라믹기술원 | Fabricating method of Hybrid metal dot pattern |
Citations (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090087582A1 (en) * | 2006-04-19 | 2009-04-02 | Shigeru Watanabe | Substrate with micrometallic masses aligned on the surface |
US20090173931A1 (en) * | 2002-04-02 | 2009-07-09 | Nanosys, Inc. | Methods of Making, Positioning and Orienting Nanostructures, Nanostructure Arrays and Nanostructure Devices |
US20100055620A1 (en) * | 2008-08-28 | 2010-03-04 | Seoul National University Research and Development Business Foundation (SNU R&DB FOUNDATI | Nanostructure fabrication |
US7917966B2 (en) * | 2008-08-21 | 2011-03-29 | Snu R&Db Foundation | Aligned nanostructures on a tip |
US8070929B2 (en) * | 2008-08-21 | 2011-12-06 | Snu R&Db Foundation | Catalyst particles on a tip |
US20120209116A1 (en) * | 2009-07-21 | 2012-08-16 | Hossack John A | Systems and Methods for Ultrasound Imaging and Insonation of Microbubbles |
US8276106B2 (en) * | 2009-03-05 | 2012-09-25 | International Business Machines Corporation | Swarm intelligence for electrical design space modeling and optimization |
US20120306082A1 (en) * | 2011-03-06 | 2012-12-06 | Monolithic 3D Inc. | Semiconductor device and structure for heat removal |
US20120313227A1 (en) * | 2011-03-06 | 2012-12-13 | Zvi Or-Bach | Semiconductor device and structure for heat removal |
US20130190595A1 (en) * | 2012-01-23 | 2013-07-25 | Alexander A. Oraevsky | Laser Optoacoustic Ultrasonic Imaging System (LOUIS) and Methods of Use |
US8569900B2 (en) * | 2009-07-20 | 2013-10-29 | Hewlett-Packard Development Company, L.P. | Nanowire sensor with angled segments that are differently functionalized |
US8629770B2 (en) * | 2004-11-29 | 2014-01-14 | Gregory J. Hummer | Sensor for container monitoring system |
US8859423B2 (en) * | 2010-08-11 | 2014-10-14 | The Arizona Board Of Regents On Behalf Of The University Of Arizona | Nanostructured electrodes and active polymer layers |
US9385058B1 (en) * | 2012-12-29 | 2016-07-05 | Monolithic 3D Inc. | Semiconductor device and structure |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004068405A2 (en) | 2003-01-25 | 2004-08-12 | Oraevsky Alexander A | High contrast optoacoustical imaging using nanoparticles |
US7959441B2 (en) | 2006-08-24 | 2011-06-14 | Medical Dental Advanced Technologies Group, L.L.C. | Laser based enhanced generation of photoacoustic pressure waves in dental and medical treatments and procedures |
JP5408565B2 (en) | 2007-09-07 | 2014-02-05 | 独立行政法人物質・材料研究機構 | Surface enhanced infrared absorption sensor material |
KR101011108B1 (en) | 2009-03-19 | 2011-01-25 | 고려대학교 산학협력단 | Nitrides light emitting device selectively using the coupling effect between surface plasmons and active layer and method for manufacturing it |
KR101223762B1 (en) | 2010-07-09 | 2013-01-17 | 성균관대학교산학협력단 | Biosensor using bragg grating waveguide for surface plasmon and detection method for target material using the same |
KR101241332B1 (en) | 2011-06-08 | 2013-03-11 | 주성엔지니어링(주) | A Solar Cell and A Manufacturing Method thereof |
KR101205392B1 (en) | 2011-08-24 | 2012-11-27 | 인하대학교 산학협력단 | Large-scale plasmonic crystal structure and manufacturing method thereof |
-
2013
- 2013-11-11 KR KR1020130136302A patent/KR20150054179A/en not_active IP Right Cessation
-
2014
- 2014-06-05 US US14/296,567 patent/US9865246B2/en active Active
Patent Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090173931A1 (en) * | 2002-04-02 | 2009-07-09 | Nanosys, Inc. | Methods of Making, Positioning and Orienting Nanostructures, Nanostructure Arrays and Nanostructure Devices |
US8629770B2 (en) * | 2004-11-29 | 2014-01-14 | Gregory J. Hummer | Sensor for container monitoring system |
US20090087582A1 (en) * | 2006-04-19 | 2009-04-02 | Shigeru Watanabe | Substrate with micrometallic masses aligned on the surface |
US7917966B2 (en) * | 2008-08-21 | 2011-03-29 | Snu R&Db Foundation | Aligned nanostructures on a tip |
US8070929B2 (en) * | 2008-08-21 | 2011-12-06 | Snu R&Db Foundation | Catalyst particles on a tip |
US20100055620A1 (en) * | 2008-08-28 | 2010-03-04 | Seoul National University Research and Development Business Foundation (SNU R&DB FOUNDATI | Nanostructure fabrication |
US8276106B2 (en) * | 2009-03-05 | 2012-09-25 | International Business Machines Corporation | Swarm intelligence for electrical design space modeling and optimization |
US8569900B2 (en) * | 2009-07-20 | 2013-10-29 | Hewlett-Packard Development Company, L.P. | Nanowire sensor with angled segments that are differently functionalized |
US20120209116A1 (en) * | 2009-07-21 | 2012-08-16 | Hossack John A | Systems and Methods for Ultrasound Imaging and Insonation of Microbubbles |
US8859423B2 (en) * | 2010-08-11 | 2014-10-14 | The Arizona Board Of Regents On Behalf Of The University Of Arizona | Nanostructured electrodes and active polymer layers |
US20120306082A1 (en) * | 2011-03-06 | 2012-12-06 | Monolithic 3D Inc. | Semiconductor device and structure for heat removal |
US20120313227A1 (en) * | 2011-03-06 | 2012-12-13 | Zvi Or-Bach | Semiconductor device and structure for heat removal |
US8975670B2 (en) * | 2011-03-06 | 2015-03-10 | Monolithic 3D Inc. | Semiconductor device and structure for heat removal |
US20130190595A1 (en) * | 2012-01-23 | 2013-07-25 | Alexander A. Oraevsky | Laser Optoacoustic Ultrasonic Imaging System (LOUIS) and Methods of Use |
US9385058B1 (en) * | 2012-12-29 | 2016-07-05 | Monolithic 3D Inc. | Semiconductor device and structure |
Non-Patent Citations (1)
Title |
---|
OâDonnell; Optoacoustic generation of high frequency sound for 3-D ;ultrasonic imaging in medicine; 2009 December 15 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3220387A1 (en) | 2016-03-15 | 2017-09-20 | Haute Ecole Arc Ingénierie | Photoacoustic device and method for manufacturing a photoacoustic device |
Also Published As
Publication number | Publication date |
---|---|
US9865246B2 (en) | 2018-01-09 |
KR20150054179A (en) | 2015-05-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9459138B2 (en) | Ultrasonic transducer, and ultrasonic wave generating apparatus and ultrasonic system including the same | |
Hou et al. | Optical generation of high frequency ultrasound using two-dimensional gold nanostructure | |
Chang et al. | Evaluation of photoacoustic transduction efficiency of candle soot nanocomposite transmitters | |
Amziane et al. | Ultrafast acoustic resonance spectroscopy of gold nanostructures: Towards a generation of tunable transverse waves | |
US9865246B2 (en) | Laser-induced ultrasound generator and method of manufacturing the same | |
JP2016531002A (en) | Interferometric laser processing | |
US20180044172A1 (en) | Capacitive transducer | |
TW201221946A (en) | Device and method for evaluating crystallinity of thin film semiconductor | |
Kang et al. | Effect of liquid thickness on laser ablation efficiency | |
Smith et al. | Optically excited nanoscale ultrasonic transducers | |
Banet et al. | High-precision film thickness determination using a laser-based ultrasonic technique | |
Devos et al. | Strong effect of interband transitions in the picosecond ultrasonics response of metallic thin films | |
Wen et al. | Three-dimensional phononic nanocrystal composed of ordered quantum dots | |
US10544811B2 (en) | Photoacoustic layer disposed on a substrate generating directional ultrasound waves | |
Wu et al. | Fiber optic photoacoustic ultrasound generator based on gold nanocomposite | |
Vallet et al. | Enhancement of photoacoustic imaging quality by using CMUT technology: Experimental study | |
Guo et al. | Broad-band high-efficiency optoacoustic generation using a novel photonic crystal-metallic structure | |
O'donnell et al. | Optoacoustic generation of high frequency sound for 3-D ultrasonic imaging in medicine | |
Yoo et al. | High-frequency optoacoustic transmitter based on nanostructured germanium via metal-assisted chemical etching | |
JP2010066252A (en) | Ultrasonic microscope | |
CN110933577B (en) | Negative-sound piezoelectric electroacoustic transducer device and preparation method thereof | |
Rossignol et al. | Interferometric detection in picosecond ultrasonics for nondestructive testing of submicrometric opaque multilayered samples: TiN/AlCu/TiN/Ti/Si | |
Bruder et al. | Assessment of laser-generated ultrasonic total focusing method for battery cell foil weld inspection | |
Xu et al. | Laser ultrasonic excitation using graphene heat dissipation film for ultrasonic detection of seismic physical model | |
KR101799075B1 (en) | Ultrasound generating device and method of fabricating the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: KOREA ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KANG, SUNG-CHAN;KIM, JONG-SEOK;KIM, CHANG-JUNG;AND OTHERS;REEL/FRAME:033034/0837 Effective date: 20140519 Owner name: SAMSUNG ELECTRONICS CO., LTD., KOREA, REPUBLIC OF Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KANG, SUNG-CHAN;KIM, JONG-SEOK;KIM, CHANG-JUNG;AND OTHERS;REEL/FRAME:033034/0837 Effective date: 20140519 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |